Audio production can involve the use of many components, including microphones, wireless audio transmitters, wireless audio receivers, recorders, and/or mixers for capturing, recording, and presenting the sound of productions, such as television programs, newscasts, movies, live events, and other types of productions. The microphones typically capture the sound of the production, which is wirelessly transmitted from the microphones and/or the wireless audio transmitters to the wireless audio receivers. The wireless audio receivers can be connected to a recorder and/or a mixer for recording and/or mixing the sound by a crew member, such as a production sound mixer. Electronic devices, such as computers and smartphones, may be connected to the recorder and/or mixer to allow the crew member to monitor audio levels and timecodes.
Wireless audio transmitters, wireless audio receivers, wireless microphones, and other portable wireless communication devices include antennas for transmitting radio frequency (RF) signals which contain digital or analog signals, such as modulated audio signals, data signals, and/or control signals. Users of portable wireless communication devices include stage performers, singers, actors, news reporters, and the like. A wireless audio transmitter may transmit an RF signal that includes an audio signal to a wireless audio receiver. The wireless audio transmitter may be included in a wireless handheld microphone, for example, that is held by the user and includes an integrated transmitter and antenna. When the RF signal is received at the wireless audio receiver, the RF signal may be degraded due to interference. This degradation may cause the RF signal to have a poor signal-to-noise ratio (SNR), which results in bit errors that can cause audio artifacts. Typically, when significant audio artifacts are present, the output audio is muted. However, muting the output audio is undesirable in many situations and environments. The effects of such interference are most prevalent in harsh RF environments where physical and electrical factors influence the transmission and reception of RF signals, e.g., movement of the microphone within the environment, other RF signals, etc.
In a conventional wireless audio system, error detection techniques are typically utilized, e.g., parity checking such as a cyclic redundancy check (CRC), to determine whether bit errors are present in a digital signal received in an RF signal at a wireless receiver. Such error detection involves analyzing the digital signal at the transmitter, generating and adding parity information to the data when it is transmitted, and recalculating the parity of the received data at the receiver. If the recalculated parity does not match the transmitted parity, then it can be determined that there are bit errors in the data. While such error detection is relatively straightforward and easy to implement, it is not optimal in wireless audio systems in particular environments, such as when maintaining the continuity of the output audio is critical.
In particular, conventional error detection may result in an increased latency due to the recalculation of the parity of the data at the receiver. Conventional error detection also suffers from poor granularity and is typically unable to specify which bits of the data are errors, which may result in the discarding of large amounts of data and undesirable audio dropouts or mutes in the output audio. As a tradeoff, it is possible to decrease the size of the data being transmitted to reduce the latency and improve the granularity attributable to conventional error detection. However, by decreasing the size of the data being transmitted, more frequent parity calculations and transmissions would be needed with a significant cost to bandwidth. Furthermore, conventional error detection techniques typically have limitations of the number of errors that can be detected. In particular, parity checking may only reliably detect a certain number of errors within the data. If the data has more than this threshold number of errors, the parity check may still deemed to have passed, in some cases.
Accordingly, there is an opportunity for a soft decision audio decoding system that addresses these concerns. More particularly, there is an opportunity for a soft decision audio decoding system that preserves audio continuity in a digital wireless audio receiver by deducing the likelihood of errors in a received digital signal with low latency and improved granularity.